Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2250/00—Layers arrangement
  • B32B2250/24—All layers being polymeric
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2250/00—Layers arrangement
  • B32B2250/24—All layers being polymeric
  • B32B2250/242—All polymers belonging to those covered by group B32B27/32
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2255/00—Coating on the layer surface
  • B32B2255/10—Coating on the layer surface on synthetic resin layer or on natural or synthetic rubber layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2255/00—Coating on the layer surface
  • B32B2255/26—Polymeric coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/40—Properties of the layers or laminate having particular optical properties
  • B32B2307/402—Coloured
  • B32B2307/4023—Coloured on the layer surface, e.g. ink
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/40—Properties of the layers or laminate having particular optical properties
  • B32B2307/406—Bright, glossy, shiny surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/40—Properties of the layers or laminate having particular optical properties
  • B32B2307/412—Transparent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/546—Flexural strength; Flexion stiffness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/724—Permeability to gases, adsorption
  • B32B2307/7242—Non-permeable
  • B32B2307/7244—Oxygen barrier
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/724—Permeability to gases, adsorption
  • B32B2307/7242—Non-permeable
  • B32B2307/7246—Water vapor barrier
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/732—Dimensional properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/75—Printability
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
  • B32B2439/40—Closed containers
  • B32B2439/46—Bags
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
  • B32B2439/70—Food packaging

Definitions

• Embodiments described herein relate generally to multilayer films for use in flexible packaging materials, and more particularly to adhesive-free multilayer films having a polyethylene film extrusion coated on a second polyethylene film for use in flexible packaging materials.
• Conventional flexible packaging materials include polymer substrates using multiple polymer families e.g., polyester (PET) as the print film and polyethylene (PE) for the sealant film. For products that may require further enhancement in barrier properties, additional layers of aluminum foil, metallized films, or barrier resins may be included. Conventional flexible packaging materials further include adhesives that may make recyclability a challenge.
• PET polyester
• PE polyethylene
• Conventional flexible packaging materials further include adhesives that may make recyclability a challenge.
• a multilayer film comprises a first film comprising at least a first layer and a second layer, and a second film extrusion coated onto the first layer of the first film, wherein the multilayer film is free of adhesives.
• the first layer of the first film comprises a first high density polyethylene (HDPE) having a density of from 0.935 to 0.965 g/cc and a melt index I 2 of 0.3 to 2.0 and the second layer of the first film comprises a polyolefin plastomer having a density of from 0.885 to 0.910 g/cc.
• HDPE high density polyethylene
• the second film comprises a second high density polyethylene (HDPE) having a density of from 0.945 to 0.965 g/cc and a melt index I 2 of 4.0 to 20.0.
• the second film has a gloss of from 65% to 95% at 60° according to ASTM D2457.
• polymer refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type.
• the generic term polymer thus embraces the term “homopolymer”, usually employed to refer to polymers prepared from only one type of monomer as well as “copolymer” which refers to polymers prepared from two or more different monomers.
• interpolymer refers to a polymer prepared by the polymerization of at least two different types of monomers.
• the generic term interpolymer thus includes copolymers, and polymers prepared from more than two different types of monomers, such as terpolymers.
• Polyethylene or "ethylene-based polymer” shall mean polymers comprising greater than 50% by mole of units which have been derived from ethylene monomer. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers).
• Common forms of polyethylene known in the art include Low Density Polyethylene (LDPE); Linear Low Density Polyethylene (LLDPE); Ultra Low Density Polyethylene (ULDPE); Very Low Density Polyethylene (VLDPE); single-site catalyzed Linear Low Density Polyethylene, including both linear and substantially linear low density resins (m- LLDPE); Medium Density Polyethylene (MDPE); and High Density Polyethylene (HDPE).
• LDPE Low Density Polyethylene
• LLDPE Linear Low Density Polyethylene
• ULDPE Ultra Low Density Polyethylene
• VLDPE Very Low Density Polyethylene
• m- LLDPE linear low Density Polyethylene
• MDPE Medium Density Polyethylene
• HDPE
• ULDPE is defined as a polyethylene-based copolymer having a density in the range of 0.895 to 0.915 g/cc.
• LDPE low density polyethylene polymer
• high pressure ethylene polymer or “highly branched polyethylene” and is defined to mean that the polymer is partly or entirely homopolymerized or copolymerized in autoclave or tubular reactors at pressures above 14,500 psi (100 MPa) with the use of free-radical initiators, such as peroxides (see for example U.S. Pat. No. 4,599,392 , incorporated herein by reference).
• LDPE resins typically have a density in the range of 0.916 to 0.940 g/cc.
• LLDPE includes both resin made using the traditional Ziegler-Natta catalyst systems as well as single-site catalysts such as metallocenes (sometimes referred to as "m-LLDPE”).
• LLDPEs contain less long chain branching than LDPEs and include the substantially linear ethylene polymers which are further defined in U.S. Pat. No. 5,272,236 , U.S. Pat. No. 5,278,272 , U.S. Pat. No. 5,582,923 and U.S. Pat. No. 5,733,155 ; the homogeneously branched linear ethylene polymer compositions such as those in U.S. Pat. No.
• the linear PE can be made via gas-phase, solution-phase or slurry polymerization or any combination thereof, using any type of reactor or reactor configuration known in the art, including but not limited to gas and solution phase reactors.
• HDPE refers to polyethylenes having densities greater than about 0.940 g/cc, which are generally prepared with Ziegler-Natta catalysts, chrome catalysts or even metallocene catalysts.
• propylene-based polymer refers to a polymer that comprises, in polymerized form, a majority amount of propylene monomer (based on the total weight of the polymer) and optionally may comprise at least one polymerized comonomer.
• flexible packaging or “flexible packaging material” encompass various non-rigid containers familiar to the skilled person. These may include pouches, stand-up pouches, pillow pouches, bulk bags, pre-made packages or the like.
• the term, "monomaterial” means that the multilayer films are composed substantially of polyethylene, wherein “substantially” means at least 95 wt% polyethylene, or at least 99 wt% polyethylene, or at least 99.5 wt% polyethylene, or at least 99.9 wt% based on the overall number of moles of the multilayer film, or 100 wt% polyethylene.
• the "print film” refers to an outer film of the multilayer film which is the film in which printing is performed in the production of flexible packages.
• the term “outer” is not to be construed as the outermost layer as some embodiments contemplate additional layers externally disposed on the print film, such as print primer layers, barrier layers, overprint varnish layers, or other layers known to the person skilled in the art of flexible packaging.
• sealant film refers to an inner film of the multilayer film structure that includes a sealant layer disposed internally relative to the print film.
• the sealant film is a monolayer film, while in other embodiments the sealant film includes multiple layers, one of which is a sealant layer.
• the sealant film may include one or more additional layers internally disposed between the layer in contact with the extrusion coating and the sealant layer, for example, barrier layers, structural layers, etc.
• extrusion coating refers to an extrusion coated layer of the multilayer film disposed on the sealant film.
• the extrusion coating is a print protection film.
• the print may be applied to the outside of the extrusion coating after the extrusion coating has been applied to the sealant film.
• adheresive refers to a polyurethane- or acrylic-based liquid adhesive that is applied between two film surfaces, for example, the extrusion coating and the sealant film and undergoes curing to bond the two film surfaces to one another.
• the multilayer film comprises a first film comprising at least a first layer and a second layer, and a second film extrusion coated onto the first layer of the first film, wherein the multilayer film is free of adhesives.
• the first layer of the first film comprises a first high density polyethylene (HDPE) having a density of from 0.935 to 0.965 g/cc and a melt index I 2 of 0.3 to 2.0 and the second layer of the first film comprises a polyolefin plastomer having a density of from 0.885 to 0.910 g/cc.
• HDPE high density polyethylene
• the second film comprises a second high density polyethylene (HDPE) having a density of from 0.945 to 0.965 g/cc and a melt index I 2 of 4.0 to 20.0.
• the second film has a gloss of from 65% to 95% at 60° according to ASTM D2457.
• the first film is a sealant film that includes at least first and second layers.
• the sealant film comprises at least three layers, specifically a middle layer, an inner layer disposed between second film and the middle layer, and an outer layer.
• the sealant film may comprise or consist of ethylene-based polymer layers.
• the first layer of the sealant film is a printed layer in various embodiments that receives an ink layer and the extrusion coating.
• the first layer may include a polyethylene composition which provides stiffness and resists gelling during the cast film or blown film extrusion processes.
• the first layer comprises at least 70% by weight high density polyethylene (HDPE) having a density from 0.935 to 0.965 g/cc and a melt index (I 2 ) from 0.3 to 2.0 g/10 min, wherein I 2 is measured according to ASTM D1238 at 190 °C and 2.16 kg load.
• HDPE high density polyethylene
• ⁇ -olefin comonomers may include C 3 -C 12 olefin monomers.
• the ⁇ -olefin comonomer in the HDPE is 1-octene.
• the first layer of the sealant film may comprise at least 95% by weight HDPE, or at least 99% by weight HDPE, or 100% by weight HDPE.
• the HDPE in the first layer provides the multilayer film with the stiffness to with withstand the stretching of the high speed printing processes.
• the HDPE of the sealant film may have a density from 0.935 to 0.965 g/cc, or from 0.940 to 0.965 g/cc.
• the melt index (I 2 ) may be from 0.3 to 4.0 g/10 min, from 0.3 to 3.0 g/10 min, from 0.3 to 2.0 g/10 min or from 0.3 to 1.5 g/10 min, or from 0.5 to 1.0 g/10 min.
• ELITETM 5960G ELITETM 5940ST
• DOWLEXTM 2740G from The Dow Chemical Company (Midland, MI)
• suitable HDPEs include those described in PCT Publication No. WO 2017/099915 , which is hereby incorporated by reference in its entirety.
• the sealant film further comprises a second layer comprising a low density polyolefin plastomer which acts as a low temperature sealing layer.
• the polyolefin plastomer can be a polyethylene plastomer or a polypropylene plastomer.
• Polyolefin plastomers may include resins made using single-site catalysts such as metallocenes and constrained geometry catalysts.
• the polyolefin plastomer has a density of 0.885 to 0.910 g/cm 3 .
• the density of the polyolefin plastomer can be from a lower limit of 0.895, 0.900, or 0.905 g/cm 3 to an upper limit of 0.905, 0.910, or 0.915 g/cm 3 .
• the polyolefin plastomer has a density from 0.885 to 0.907 g/cm 3 or from 0.885 to 0.902 g/cm 3 .
• the polyolefin plastomer has a melt index (I 2 ) of up to 20 g/10 minutes. All individual values and subranges up to 20 g/10 minutes are included herein and disclosed herein.
• the polyolefin plastomer can have a melt index to an upper limit of 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 g/10 minutes.
• the polyolefin plastomer has an I 2 with a lower limit of 0.5 g/10 minutes.
• One factor in identifying a melt index for the polyolefin plastomer is whether the second layer will be manufactured as a blown film or a cast film.
• polyolefin plastomers that can be used in the second layer include those commercially available from The Dow Chemical Company under the name AFFINITYTM including, for example, AFFINITYTM PL 1881G and AFFINITYTM PF1140G.
• the sealant film may include additional layers between the first and second layers.
• the sealant film may include a third layer that includes one or more ethylene-based polymers.
• the third layer may include HDPE, LDPE, a combination of HDPE and LDPE, or the like.
• the sealant film may include three additional layers in between the first and second layers, two of which are tie layers which bond a barrier layer (e.g., an EVOH layer) to the first and second layers. Additional layers are contemplated, although it should be understood that such additional layers are optional in some embodiments.
• a second film is extrusion coated onto the first layer of the first film.
• the second film which may in some embodiments be considered a print protective film, provides the aesthetic benefits (e.g., gloss and clarity) to the multilayer film.
• the second film may enable the multilayer film to achieve a gloss value of at least 65%, wherein gloss is measured at 60° according to ASTM D2457.
• the second film comprises a second high density polyethylene (HDPE) having a density of from 0.945 g/cc to 0.965 g/cc and a melt index I 2 of 4.0 to 20.0 g/10 min, where I 2 is measured according to ASTM D1238 at 190 °C and 2.16 kg load.
• HDPE high density polyethylene
• the second film comprises an inner layer and an outer layer, which may have the same formulations or different formulations.
• the inner layer is in contact with the first layer of the sealant film.
• the outer layer in some embodiments, comprises the second HDPE. In one or more embodiments, the outer layer comprises, or consists of, 100% by weight of the second HDPE. However, in other embodiments, outer layer may include the second HDPE and an LDPE or other polyethylene-based polymer. In such embodiments, the outer layer may comprise from 50 % to 99 %, from 55 % to 95 %, from 60 % to 90 %, from 65 % to 85 %, or from 75% to 95 % by weight of the second HDPE.
• the inner layer has a thickness of from 5 ⁇ m to 10 ⁇ m, or from 7 ⁇ m to 9 ⁇ m.
• the outer layer may have a thickness of from 1 ⁇ m to 5 ⁇ m, or from 2 ⁇ m to 4 ⁇ m.
• the thickness of the second film may vary depending on the particular embodiment. However, in various embodiments, the second film has a coat weight of from 9 g/m 2 to 20 g/m 2 , from 10 g/m 2 to 18 g/m 2 , or from 11 g/m 2 to 15 g/m 2 . In some embodiments, the second film has a coat weight of less than 12 g/m 2 . Such coat weights enable the second film to provide protection for the ink while maintaining good clarity.
• the inner layer of various embodiments includes an HDPE and a low density polyethylene (LDPE).
• the HDPE of the inner layer has a density of from 0.935 to 0.965 g/cc, or from 0.940 to 0.965 g/cc.
• the melt index (I 2 ) may be from 4.0 to 15.0 g/10 min, or from 5.0 to 15.0 g/10 min.
• the HDPE and the LDPE of the inner layer may be blended together to form the inner layer, or the HDPE and the LDPE may be coextruded to form the inner layer.
• the LDPE of the inner layer of the second film may have a density from 0.915 to 0.930 g/cc, or from 0.915 g/cc to 0.925 g/cc.
• the melt index (I 2 ) of the LDPE may be from 1.0 to 15.0 g/10 min, or from 1.0 to 10.0 g/10 min, or from 2.5 to 10.0 g/10 min.
• the LDPE compositions may include antiblock agent, slip agent, or both.
• Various commercial LDPE products are considered suitable for the inner layer of the second film, for example, AGILITYTM EC7000, AGILITYTM EC7220, DOWTM LDPE 7008 and DOWTM LDPE 7004, all of which are available from The Dow Chemical Company (Midland, MI).
• the second film may include less than or equal to 30% by weight LDPE, or less than or equal to 25 % by weight LDPE.
• the inner layer may comprise from 5 to 30% by weight LDPE.
• the inner layer may include from 5 to 25% by weight LDPE.
• the inner layer may include from 5 to 10% by weight LDPE.
• the LDPE may provide improved optical properties, such as gloss and clarity, while also enhancing processibility of the extrusion coating.
• the extrusion coating may be a monolayer film.
• the HDPE and LDPE may be blended together to form a single layer instead of being coextruded as multiple layers.
• the second film has a gloss of from 65% to 95% at 60° according to ASTM D2457. In some particular embodiments, the second film has a gloss of from 70% to 90% or from 80% to 85%.
• the second film may further have a melting point (highest differential scanning calorimetry (DSC) melting peak temperature) of from 110 °C to 135 °C.
• DSC differential scanning calorimetry
• the multilayer film includes greater than 95% by weight of ethylene-based polymer based on the total weight of the multilayer film. In some embodiments, the multilayer film includes greater than 98% by weight of ethylene-based polymer, or even greater than 99% by weight of ethylene-based polymer based on the total weight of the multilayer film.
• the multilayer film may include more than the first and second layers described herein above.
• the multilayer film may include a layer of ink between the first film and the second film.
• the layer of ink may be, for example, in the form of images or words.
• the layer of ink may be printed on the first film and the second layer may be extruded over the layer of ink, as will be described in greater detail below.
• the multilayer films are imparted with a unique combination of high gloss and high stiffness without the use of adhesives.
• the multilayer film may have an apparent bending modulus of greater than 0.014 N/mm 2 for a multilayer film having a thickness of less than 150 ⁇ m as measured in accordance with ASTM D747.
• the multilayer sealant films may prepared by cast film extrusion, or blown film extrusion.
• the multilayer extrusion coated films may be prepared by flat die film extrusion.
• the sealant film may undergo a printing process.
• Various printing processes are considered suitable for the cast or blown print films. These printing processes may include, but are not limited to rotogravure printing, flexographic printing, and offset printing.
• the sealant films may undergo rotogravure printing.
• the sealant films are reverse rotogravure printed at the print speeds typically utilized for a conventional PET/PE laminate. The tension between rollers in the rotogravure machine may cause overstretching of conventional films leading to poor print registration.
• the present sealant films are believed to have the requisite stiffness to prevent overstretching and thereby achieve the desired printing performance.
• the present sealant films may stretch less than 2 mm on a rotogravure print machine whereas conventional polyethylene print films which may stretch about 6 mm.
• the extrusion coated film may be coated directly on the sealant film and the multilayer film undergo a printing process such that the print is applied over extrusion coated film.
• the extrusion coated film may not provide protection to the layer of ink.
• test methods include the following:
• Melt index (I 2 ) was measured in accordance to ASTM D-1238 at 190°C at 2.16 kg.
• Melt index (I 10 ) was measured in accordance to ASTM D-1238 at 190°C at 10 kg. The values are reported in g/10 min, which corresponds to grams eluted per 10 minutes.
• Samples for density measurement were prepared according to ASTM D4703 and reported in grams/cubic centimeter (g/cc or g/cm 3 ). Measurements were made within one hour of sample pressing using ASTM D792, Method B.
• Gloss was measured at 60° according to the ASTM D2457 method. Reported values are the average of the gloss measured for five samples.
• DSC is used to measure the melting and crystallization behavior of a polymer over a wide range of temperatures.
• the TA Instruments Q1000 DSC equipped with an RCS (refrigerated cooling system) and an autosampler is used to perform this analysis.
• the instrument is first calibrated using the software calibration wizard. A baseline is obtained by heating a cell from -80 °C to 280 °C without any sample in an aluminum DSC pan. Sapphire standards are then used as instructed by the calibration wizard.
• a nitrogen purge gas flow of 50 ml/min is used. Each sample is melt pressed into a thin film at about 175 °C; the melted sample is then air-cooled to room temperature (approx. 25 °C). The film sample is formed by pressing a "0.1 to 0.2 gram" sample at 175 °C at 1,500 psi, and 30 seconds, to form a "0.1 to 0.2 mil thick" film. A 3-10 mg, 6 mm diameter specimen is extracted from the cooled polymer, weighed, placed in a light aluminum pan (ca 50 mg), and crimped shut. Analysis is then performed to determine its thermal properties.
• the thermal behavior of the sample is determined by ramping the sample temperature up and down to create a heat flow versus temperature profile. First, the sample is rapidly heated to 180 °C, and held isothermal for five minutes, in order to remove its thermal history. Next, the sample is cooled to -40 °C, at a 10 °C/minute cooling rate, and held isothermal at -40 °C for five minutes. The sample is then heated to 150 °C (this is the "second heat" ramp) at a 10 °C/minute heating rate. The cooling and second heating curves are recorded. The cool curve is analyzed by setting baseline endpoints from the beginning of crystallization to -20 °C. The heat curve is analyzed by setting baseline endpoints from - 20 °C to the end of melt.
• the heat of fusion (H f ) and the peak melting temperature are reported from the second heat curve. Peak crystallization temperature and onset crystallization temperature are determined from the cooling curve.
• Oxygen Transmission Rate is measured at 23 °C at 75% RH according to ASTM D3985.
• Water Vapor Transmission Rate is measured at 38 °C at 90% RH according to ASTM E-398.
• the apparent bending modulus is measured in accordance with ASTM D747.
• Example 1 a multilayer film (Example 1) in accordance with the present disclosure was compared with a conventional PET/PE laminate having a conventional PE film adhered to a conventional PET print film (Comparative Example 1), a PE/PE laminate having a conventional PE film adhered to a conventional PE print film (Comparative Example 2), and a lacquer-coated conventional PE print film (Comparative Example 3).
• Table 1 lists the compositions of these multilayer films studied herein.
• the sealant layer includes three layers, A, B, and C, in which layer C is a low temperature sealing layer.
• Layer A includes 98.5% HDPE1, 1% POLYBATCH AMF 705 HF, and 0.5% POLYBATCH VLA 55.
• Layer B includes 84% HDPE1 and 16% POLYBATCH NG 8160.
• Layer C includes 84% AFFINITY 1881G, 14.5% LDPE 310E, 1% POLYBATCH AMF 705 HF, and 0.5% POLYBATCH VLA 55.
• the sealant layer of Comparative Example 1 is a film including a low temperature sealing layer and layers containing LLDPE and/or LDPE.
• the lacquer of Comparative Example 3 is a commercially available lacquer for providing thermal resistance.
• the extrusion coating was a blend of 20 wt% AGILITYTM EC 7220 (an LDPE having a density of 0.918 g/cm 3 measured in accordance with ASTM D792 and a melt index I 2 of 1.5 g/10 minutes measured in accordance with ASTM D1238 at 190 °C and 2.16 kg) and DOWLEXTM 2006 (a polyethylene product having a density of 0.961 g/cm 3 measured in accordance with ASTM D792 and a melt index I 2 of 8.0 g/10 minutes measured in accordance with ASTM D1238 at 190 °C and 2.16 kg).
• AGILITYTM EC 7220 an LDPE having a density of 0.918 g/cm 3 measured in accordance with ASTM D792 and a melt index I 2 of 1.5 g/10 minutes measured in accordance with ASTM D1238 at 190 °C and 2.16 kg
• DOWLEXTM 2006 a polyethylene product having a density of 0.961 g/cm
• Table 2 The film extrusion processes used to make the multilayer films of Table 1 were conducted on a Kaschier (Germany) blown film line.
• the blown film line had the following properties as listed in Table 2 as follows.
• Table 3 lists the temperature profile of the blown film line i.e., the temperatures at different locations of the blown film line.
• Example 1 an extrusion coating having the composition described in Table 1 was applied to the blown film using the following conditions: SML extrusion coating line; coating melt temperature of 309 °C; air gap of 280 mm; and chill roll temperature of - 16-18 °C.
• Example 1 In the present experiments, gloss, oxygen transmission rate (OTR), water vapor transmission rate (WVTR), and stiffness were measured on Example 1 and Comparative Examples 1-3.
• Table 4 Table 4: Mechanical and Optical Properties of Multilayer Films Example 1 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Gloss 83.8 81.6 11.8 58.4 OTR at 23 °C and 75% RH (cc/m 2 /day) 593 134 635 625 WVTR at 38 °C and 90% RH (g/m 2 /day) 1.57 3.38 1.45 1.4 Bending Modulus (N/mm 2 ) 0.015 0.014 0.013 0.015
• Example 1 including the extrusion coating exhibits improved gloss at 60° as compared to Comparative Example 2 and Comparative Example 3 while maintaining a similar OTR or WVTR.
• the extrusion coating further exhibits similar apparent bending modulus to each of the comparative examples.
• various embodiments described herein provide for multilayer polyethylene film structures that achieve desired sustainability, strength, and optical properties, such as gloss, without the use of adhesives.

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